Forensic Science Blood Typing Lab Activity

T. Trimpe 2006 http://sciencespot.net/

A small pool of blood and a weapon was found near a garbage dumpster. After examining the area, the CSI on the scene discovered a body in the garbage dumpster and identified him as Earnest “One-Eyed” Earl. Earl had a wound to his chest that will be analyzed by the medical examiner.

The CSI tested blood samples from the blood pool and the weapon at the crime scene. It was determined that it was human blood, but he needs to know the blood type to help identify if it was from the victim or the person who murdered him. He has come up with three suspects that either knew the victim or were seen in the area before the body was discovered. He would like to question them further while he waits for DNA test results.

Follow your teacher’s directions to complete the lab. Remember to be careful to prevent cross-contamination of the blood samples!

Image: http://www.fbi.gov/publications/leb/2005/apr2005/apr2005leb_img_3.jpg

The Crime Report

We will be determining blood types using Anti-A serum, Anti-B serum, and Anti-RH serum. Use the chart to help you determine the blood type of each sample and its Rh factor (+ or -).

Clumping = + (Positive) No Clumping = - (Negative)

DIRECTIONS:

Step 1: Label the three cups in your kit as Anti-A, Anti-B, and Anti-Rh.

Step 2: Place 20 drops of the blood sample in each cup.

Step 3: Place 10 drops of the anti-A serum in the A cup.

Step 4: Place 10 drops of the anti-B serum in the B cup.

Step 5: Place 10 drops of the anti-Rh serum in the Rh cup.

Step 6: Use a clean toothpick for each sample and stir for 30 seconds.

Blood Typing Test

Rh Serum - Clumping = Rh+ blood

TypeReaction w/

Anti-A SerumReaction w/

Anti-B Serum

A + -

B - +

AB + +

O - -

Step 7: Record your observations in the correct section on the back of the page and use the reaction chart at the top of this page to determine the blood type.

Step 8: Complete the other sections using information from your classmates.

Agglutination = Clumping = Positive Reaction

Clumping = Positive Result

A

B

Rh

What is this person’s blood type?

Answer: A+

Rh Serum - Clumping = Rh+ blood

TypeReaction w/

Anti-A SerumReaction w/

Anti-B Serum

A + -

B - +

AB + +

O - -

What do your results show?

What would you do next in the investigation?

Conclusion

- = No clumping

+ = Clumping

Results

Use + or – to show the test results for each sample and then determine the blood type.